I would like to present another alternative to the machined discs that only requires the use of an angle grinder, and hand drill. This procedure takes about 2 hours for all four discs, and is very effective if you don't mind spending a little quality time with your angle grinder. Since the hub flanges required in the plans vary in size, I will not be posting measurements here, but the same procedure will work on all trikes that use the hub-axle system I have developed.
To see some of the trike and quadcycle projects that these hubs are used on, please visit http://www.atomiczombie.com .
Step 1: Marking the flatbar to make the discs
The center of the disc must be marked and punched before any cutting, as you do not want to loose this center position. The punched center will later be drilled for the axles. Also, use a marker that can hold up to a little abuse as you will be grinding and handling the discs with gloves.